How to label and grow tomatoes from seed?

If you've ever neglected to label a tray of seeds, or mixed them, you understand the frustration of not knowing what will come up when.

When you grow tomatoes from seed it's easy to jumble varieties.

If you are growing other vegetables from seed, too, then you might have some real confusion on your hands.

Are those germinating seedlings tomatoes, bell peppers, squash, cucumbers, eggplant, or a mystery vegetable?

Not only are there good reasons to label your tomato seedling trays, but it's really easy to do ... once you have a system.

Why label planted tomato seeds?

• To know what you've got. Mark tomato varieties so you can plant them your pre-chosen spots in the garden, especially when you've started more than one or two varieties. Unmarked plants have less of a chance for success in the garden or on the patio.
• To care for what you've got. Mark tomatoes to increase the likelihood that you’ll care for each variety as it needs. Heirloom tomatoes, for instance, can be more susceptible to diseases and need extra monitoring.
• To track performance. Find out what varieties work best in your garden. Use your notes about starting dates, germination, hardening off and planting in the garden to maximize decisions in coming seasons.

How to label tomato seeds in trays

What to use
Make free or inexpensive labels from popsicle sticks, plastic sticks cut from used yogurt containers, masking tape, ½” strips cut from aluminum pie pans, or write on the pots themselves (as in the case of plastic or paper cups or recycled cartons).

Best marking tools
What’s the point in labeling your tomatoes if markings get rubbed off when you handle the pots or rinsed off when you water the plants? Then, mid-summer you wonder which tomato varieties are which, creating all kinds of confusion. Use markers that are long-lasting, like industrial-strength paint markers identified as “non-fading,” marking pens created especially for garden labeling, or Sharpie® Industrial pens (regular Sharpies® have been known to fade in 4-6 weeks).

Tagging tips

• Insert popsicle stick, plastic stick or aluminum strip into the soil. You’ll be able to reuse them when you set plants out into the garden. Or attach masking tape to pot or write name directly on pot. If you use aluminum strips cut from recycled pie plates, use a sharp pointed object to inscribe name in the metal.
• When sowing seeds in a flat, mark the entire flat. Figure out a way to show which section of the flat is which variety.
• When you move each plant into its own pot, mark it.
• Make sure labels surfaces are dry when you mark them.

Taking notes
Do it. You’ll be glad you did. Use a small notebook or even a loose sheet of paper. Record the following information:

• tomato variety
• planting date
• germination date
• date first true set of leaves appear
• transplanting date
• special plant strengthening tips
• feeding
• hardening off dates and exposure
• planting date
• flowering date
• first pick
• last pick
• pests
• diseases

Tomato growing tips for seeds

These tomato growing tips will help you start tomato plants from seeds and grow healthy tomato seedlings. When it comes to starting tomatoes from seeds, you have two responsibilities:

• Take care of seeds so they germinate
• Keep emerged seedlings healthy until they’re ready to set out in the garden

5 tomato growing tips for germination

Your biggest challenge in getting seeds to germinate is to create the best circumstances possible to help them along. That means eliminating any variables that inhibit sprouting. Use these tomato growing tips to maximize your germination conditions.

Choose your germination spot wisely

New growers may be tempted to start seedlings in a cool, damp basement or drafty upstairs room. Even with growing lights, these environments are not your best bet. Humidity and low temps are the perfect breeding ground for fungi and bacteria – particularly the fungi responsible for damping off. Inadequate heat and drafts can slow germination. Pick a spot to start your seeds that has balanced humidity and good air circulation.

Start clean

Use quality, sterile potting mix to start your seedlings. Garden soil is packed with bacteria and fungi that prey on tomato seeds and seedlings. Don’t use it. While choosing a potting mix, select one with a neutral pH. Acid soils are ideal for fungus growth – something you want to avoid. Make sure containers are clean. It’s OK if they’re used. Just wash them thoroughly and sterilize them before filling them with potting mix.

Plant sparingly

Sow just one or two seeds per cell to give them breathing room to sprout.

Sprinkle soil surfaces

Spread a thin layer of sand, perlite, or sphagnum peat moss on the surface of the soil to discourage fungi and bacteria. Sand and perlite keep the stems dry at the soil surface where damping off occurs. Peat moss has anti-bacterial qualities.

Check labels

Wooden popsicle sticks are easily infected. When used to label tomato seedlings, they are susceptible to bacteria and fungus. Discourage the spread of disease by using plastic labeling sticks.

Tomato growing tips for seedlings

Once seedlings emerge, the biggest challenge is disease – primarily fungal problems related to damping off. Affected seedlings looked pinched, flop over, wither, or appear cut off at the soil surface. Most die quickly. Once the fungus has taken hold, it is usually quick-spreading and fatal. Damping off often impacts an entire flat. Use these tomato growing tips to prevent damping off and other diseases in your new tomato seedlings.

Thin seedlings

When seedlings are crowded, stems and leaves don’t dry quickly. They retain moisture and promote humid conditions – the perfect environment for nasty germs to thrive and attack plants. When seedlings emerge, let the strongest one grow. Pluck out extras with your fingers or tweezers.

Keep air moving

Humid, stagnant air creates an ideal environment for fungi and bacteria to flourish. When starting seedlings, prop the top of the seed-starting tray up a few inches to allow air to flow. Or punch holes in the plastic cover. Once seedlings emerge, place an electric fan near the tray and set it on a gentle breeze. Air circulation discourages bacteria and fungi.

Don’t overwater

Too much water fills the air pockets in potting soil and chokes new roots.

Water from below

Wet foliage encourages bacteria and fungi. Do everything you can to prevent stems and leaves from getting wet. Once seedlings emerge, stop misting soil surface. Instead, pour water into the seedling tray. Let plants absorb water. Watering from below strengthens a tomato plant’s root system, too.

Monitor surfaces

When white mold or other fluffy growth appears on plants, markers, pots, or the soil surface, separate those containers from the rest of your crop. This way you have a chance to protect unaffected plants. Meanwhile, destroy infected plants. Do not reuse the affected potting mix. Disinfect containers with a bleach solution before replanting new seeds.

Seed starting mix for tomatoes: what ingredients are important

The best seed starting mix for tomatoes has four qualities:

• It is sterile
• It absorbs moisture
• It drains well
• It retains moisture

The most common base ingredients in commercial mixes are sphagnum peat moss, perlite, vermiculite, and lime. Another potting mix ingredient that is growing in popularity is coco coir (also called coconut coir, potting coir, or simply coir.) A seed starting mix with these ingredients is often labeled as “soil-less.” In the truest sense, these ingredients contain no soil or dirt and are considered to be sterile. They are not jam-packed with living organisms. Garden soil, on the other hand, is filled with organic matter and is home to active bacteria and fungi. That means if you grow tomato seeds in garden soil, they’re much more susceptible to the dreaded damping-off disease that kills so many seedlings.

Sphagnum peat moss

Most sterile commercial seed starting mixes are peat-based with added ingredients for aeration.

Peat is partially decomposed organic matter. It has been compressed in low-lying ground where water sits, containing hardly any oxygen. That slows decay, leading to partially-carbonized composites. The resulting material, peat moss, is organic and acidic. Its acidity inhibits bacteria and fungi – a plus for new plants. When dry it forms a water-repellent crust.

Specifically, sphagnum peat moss is derived from sphagnum moss and considered to be a high quality peat. It is the most preferred type of peat for horticultural purposes. Sphagnum peat can hold up to 20 times its dry weight in water. Its ability to absorb water helps keep new seedlings moist. But sphagnum peat moss works best for seed starting when combined with other ingredients to retain water (not just absorb it), loosen the mixture, and give roots some breathing room.

Perlite

Perlite, a form of volcanic glass, is a mined material. Its strength is aeration. Perlite allows a seed starting mix or potting mix to have tiny air pockets and keep the mixture drained. This prevents overwatering that can easily lead to drowning for new seedlings and plants grown in containers. Perlite is also very inexpensive. Its biggest drawback is also its strength: it doesn't retain water well, which means it dries out quickly. That’s why it’s most useful when combined with ingredients that hold moisture, like sphagnum peat moss and vermiculite. Use a dust mask when handling dry perlite since it can easily be inhaled.

Vermiculite

Vermiculite is a naturally-occurring, shiny, flaked mineral that resembles mica. It retains moisture well (about 200% - 300% by weight). It’s also inexpensive. Vermiculite’s water-retentive properties allow it to easily distribute nutrients to plants. The major drawback of vermiculite is that it retains too much water if used solely on its own and can suffocate the roots of plants. It’s most effective if used in combination with other ingredients. Use a dust mask when handling dry vermiculite since it can easily be inhaled.

Coco coir

Coco coir is coconut husk residue. Gardeners are excited about coco coir (pronounced “kwaher”) because it drains well and needs less watering than most potting mixes. Another significant advantage to coir is that it is a renewable resource. Coco is a by-product of the coconut-processing industry. As coconuts are grown and harvested, more coco coir is produced.

Why these four ingredients complement each other

Sphagnum peat moss, vermiculite, perlite, and coir complement each other well in a seed starting mix. Sphagnum peat absorbs water. Perlite allows adequate drainage, which lets roots have plenty of oxygen. Vermiculite retains moisture so that plants don’t dry out but have access to nutrients. Coir retains moisture, offers good drainage, doesn't compact, and is a renewable resource.

Well-balanced, prepared mixes such as Natural Beginnings Seed-Starting Mix and Eco-Co Coir combine these ingredients.

Fertilizer

Most seed starting mixes contain trace nutrients at most. There’s little need for added nutrients at this early stage because a plant’s initial nourishment is already packed inside the seed itself. But once seedlings have two sets of true leaves, it’s time to feed them a bit. You can add a bit of compost when you transplant tomato seedlings to their next size container or include a small amount of water-soluble fertilizer (such as Miracle Gro for tomatoes) in your moistening regimen.

Check for lime

If you select a peat-based seed starting mix, check the label. Make sure it contains a little lime to reduce the acidity and create a balanced combination – or add a dash on your own – because sphagnum peat moss is acidic.

What potting mix to use when starting tomato seeds?

Potting mix’s main jobs are to –

• Get the seeds to sprout
• Keep them disease-free until they have 2 sets of leaves.

Tomato seeds simply need light, soil, moisture, and protection from disease in order to germinate. A good mix helps make those things possible.

Your best choice when growing tomatoes from seeds: sterile potting mix. You can purchase a commercially-prepared sterile seed starting mix or make your own.

How to choose a seed starting mix?

Commercially-prepared starting mixes vary in composition.

Make sure you select a potting mix, not potting soil (which is heavier).

Choose a mix that is lightweight, holds water, and is light on fertilizer. You don’t want your tomato seedlings to get too overfed while they still can get nutrients from the seed.

Commonly-used mixes are –

• Hyponex potting mix: peat, compost, sand, perlite
• Jiffy Mix: peat moss, perlite
• Pro-Mix: peat-based with bio-fungicide
• MetroMix: peat, vermiculite, sand, light fertilizer
• Fafard: sphagnum peat, perlite, compost
• Coco coir-based mix

How to make your own seed starting mix

Pick a recipe and combine ingredients in a large sterile tray, pot, or bucket.

• Easy seed starter mix: 1 part sphagnum peat, 1 part vermiculite, 1 part perlite (parts by volume, not weight)
• Cornell University seed starter mix: 2 parts peat moss, 1 part perlite, 1 part vermiculite (parts by volume, not weight), 1 teaspoon lime, 1 teaspoon 0-20-0 fertilizer, 2 teaspoons 19-6-12 fertilizer (slow release)

Why not use garden soil?

Garden soil is not sterile. Try to avoid using it if possible because it’s full of weed seeds, it compacts (preventing good circulation), and worst of all – it contains nasty disease-carrying organisms, bacteria, and fungi, which have a bad reputation for causing damping-off disease.

If you must use garden soil, sterilize it before planting. Place soil in a shallow pan. Bake at 180°F for 45 minutes. Make sure soil reaches 180°F so all the nasties are zapped. But don’t overcook, or you’ll release toxins in the soil.

What to do after choosing a starting mix

Whichever potting mix you use, make sure you moisten it well. Add warm water and stir with a sterile trowel or large wooden spoon until the mixture is evenly damp, like a wrung-out sponge. Press it lightly into your seed starting containers.

Keep extra sphagnum peat moss on hand when growing tomatoes from seeds and sprinkle it on top of your prepared seed cell trays. Its anti-fungal properties are helpful in keeping seeds and seedlings disease-free.

Tomato seed starting basics

When it comes to growing tomatoes, you’ve got three choices:

• grow tomatoes from seeds indoors while it’s still cold outside
• grow tomato plants in a greenhouse or cold frame
• buy tomato plants from a nursery or garden center once the weather is warm enough 

Growing tomatoes from seeds is easy. It just takes planning and a bit of stick-to-it-ive-ness. You’ll soon find out that you can grow tomatoes yourself for a lot less and they taste much better than what you find in the grocery store.

Best reasons to grow tomatoes from seeds

Longer season. Start seeds sooner, seedlings germinate sooner, voila – plants produce tomatoes sooner and longer. That’s especially helpful if your growing season is short say, in the north. Cool spring temperatures slow germination or can kill young seedlings. An early fall frost can zap mature tomato plants. When you get a head start indoors, you max out production and get an extended tomato harvest.

Cheaper plants. You can save money by starting your tomatoes from seed if you like to grow lots of tomatoes or if you like to try different varieties. You can also save money by making your own planting mix. You won’t save money if you buy designer starter mix or use top-of-the-line seed starter trays. Bonus money saver: when you start tomatoes from seed, you get stronger tomato plants for less.

More variety. There are more than thousands of varieties of tomatoes. It’s fun to try to new kinds!

A cure for winter. A few weeks after the new year, my fingers are itching to dig in the dirt. Starting tomato seeds indoors takes the edge off.

Seed starting step-by-step

Plan ahead for successful seed starting
The first step you need to take to successfully grow a tomato plant from start to finish is to choose your tomato seeds. Take time to find out about different tomato varieties. Experienced gardeners order seeds from garden catalogs as early as December for the following spring. You can also find seeds online at seed exchange sites or from other avid gardeners. Nurseries and home improvement centers sell seeds, too.
Start tomato seeds 6-8 weeks before planting time
Check your local frost dates. Start tomato seeds about 6 weeks before it’s safe to set out plants in the garden.

Plant tomato seeds: easy steps to take
Get the scoop and simple step-by-step instructions that explain how to --

• choose containers for seed starting
• what potting mix to use
• how to plant your seeds
• label your newly-planted seeds (especially if you’re growing different varieties)

What to look for after seeds are planted
Your tomato seedlings will emerge in 5-10 days. You’re now in the “stick-to-it-ive-ness” period of seed starting. For the next month, you’ll need to check your new seedlings daily. Mist or water them regularly. Once they have 2 sets of leaves, re-pot them in 4-6" transplant pots to help them build strong root systems. Monitor them carefully to check for the biggest seed-starting problems, like tomato fungus, legginess, slow growth, and seed rot.

Prepare for next year
As you harvest your tomato crop, save some seeds for next year. Have extras on hand to share with gardening friends. You might even inspire someone you know to give seed starting a try!

Compare seed starting kits for growing tomatoes

Seed starting kits offer an excellent value if you want to grow your own tomato plants from seeds. By purchasing a kit, you save money over the price of buying individual components.

And kits are convenient. In one package, you get all you need to start tomato seeds. Beginners, in particular, are drawn to kits because using them makes starting tomato seeds much less intimidating.

Seed starting kits come with trays that have different numbers of cells. You can choose a kit offering the number of cells that meets your needs. If you want to start only a few plants, buy a kit with a smaller number of cells. If you’re interested in growing large numbers of tomatoes, as do commercial growers, you can use 128-cell trays. And seed starting kits come with all different numbers of cells in between.

Durability is another advantage. If you buy a quality kit to start with, you can re-use it each year when you start your tomato seeds.

What features to look for in seed starting kits

There are lots of kits out there. Consider two especially important features as you choose yours: the kit’s planting tray system and its cell size.

1. Planting tray system. The traditional kit offers a planting cell tray and a reservoir tray. The planting cell tray is made up of individual units, or cells, that will accommodate individual seedlings. Each cell has holes in the bottom for drainage. The planting tray is set inside a reservoir tray, which captures moisture that seeps through the holes after watering. Traditional seed cell trays are offered by Gardener's Supply, Burpee, and other gardening vendors online (look at a range of seed cell trays.)

Traditional kits also have developed extra features. Burpee's 25 Cell Netted Greenhouse, while not self-watering, uses netted cells to give roots enough circulation.

Newer kit styles offer a self-watering system. These prevent potting mix from drying out – a key factor in tomato seed starting success. Like traditional seed cell trays, self-watering systems have a cell tray and a reservoir tray. What makes them different is their self-watering system, set up to wick water from the reservoir tray up through the planting cells. Planting cells rest on a hydration mat (and in some cases, an additional pegboard) on top of the reservoir tray. The hydration mat’s edges sits in the tray's water, wicking up enough moisture to keep the seed starting mix damp. This allows the planting medium to stay moist for about five days. Both APS Seed-starting System from Gardener’s Supply and Burpee’s Ultimate Growing System use self-watering systems.

2. Size. Tomatoes are fast-growing. They outgrow small planting cells quickly. It’s a good idea to use trays with the biggest cells possible. The larger the individual cell (2-4 inches in diameter), the more opportunity for each seedling to spread its root systems without having to be disturbed and re-potted. Seedlings grown in very large cells (3-4 inches wide) often do not need to be re-potted at all before being set out in the garden. Keep in mind that the larger the cell, the fewer cells a tray holds – meaning trays with large cells will accommodate fewer plants.

(But starting tomato seedlings in 1- or 1 ½-inch cells is not a recipe for gardening disaster. Once seedlings have two sets of seedlings, they can be successfully re-potted to larger containers and can grow excellent root systems.)

When it comes cell depth, deeper is better, too. Deep cells encourage tomato roots to reach down into the water reservoir, whether it’s a traditional tray set up or a self-watering system. That means root systems grow stronger, which is always better for tomato seedlings.

Additional features to consider in seed starting kits

Planting medium. A sterile, soil-less growing medium prevents diseases and damping off. Kits from Gardener’s Supply include GS Professional Germinating Mix, a finely textured, pH-adjusted sterile blend of sphagnum peat and vermiculite.

Coconut coir, a natural fiber extracted from coconut husks, is quickly becoming a popular seed starting medium. The fibers allow for good root aeration.

Greenhouse cover. Some kits come with a clear plastic lid, which acts like a greenhouse cover. It holds in humidity during the early stages of germination and growing. The cover is a helpful option. It gives seeds the opportunity to germinate more quickly. Once seedlings grow large enough to touch the greenhouse lid, you can leave it off.

Nice extras in seed starting kits

Plant fertilizer. As tomato seedlings emerge, they don’t need extra nutrients because they’re getting nutrients from the seed itself. After about three weeks to a month, they can be fertilized with a reduced-concentration solution. An extra fertilizer packet that comes with a kit is a nice add-on, but it’s not a deal-maker when choosing a kit. The Burpee kits comes with a one pack of organic fertilizer. Gardener’s Supply kits also provide a small, 2.5 oz. of plant health care nutrient supplement.

Plant labels. Another “nice to have but not completely necessary feature.” Gardener’s Supply gives you 24 wooden markers. Burpee’s provides three.

Tray material. Some are made of plastic; others are made from biodegradable resin, which will break down in a landfill or, eventually, in a compost heap. (Don’t’ confuse biodegradable resin with individual seed starting pots made from peat, plant fiber, coir, or paper that break down when you plant them in the garden.)

Heat mat. A heating pad placed underneath seed starting trays, as offered by Hydrofarm Germination Station, helps seeds germinate quicker. It’s helpful to use a seedling heat mat no matter what seed starting system you choose.

Seed starting containers to use when you sow tomatoes

Seed starting containers need to be sterile and have good drainage.
Their three main jobs are to:

1. Be home to your seedlings while they germinate
2. Keep away diseases
3. Help tomato sprouts grow 2 sets of leaves

Top seed starting container tips

• Start seeds in individual containers rather than open flats. If you start tomato seeds in open flats, you’ll need to split plants after they germinate and separate their root systems, which stresses new tomato seedlings. Transplanting is much easier when each sprout is contained in its own cell or cup. Seed cell trays are ideal and can be re-used year to year.
• Calculate volume. If you’re starting a lot of tomatoes (and other crops), use flats with individual cells to accommodate large numbers of plants.
• Set your containers in a tray, plastic box, or rimmed cookie sheetfor balance and good drainage. A tray also lets you water from the bottom. That helps your seedlings produce strong root systems. Roots will need to reach down into the growing medium for water.
• Sterilize plastic containers that you re-use from last year in a 5-10% bleach solution. You’ll help keep nasty bacteria and fungi away.
• Go simple and cheap. There’s no need to go fancy with starting containers. Use something clean with good drainage. Remember to poke holes.

Any small container works!

• Try Styrofoam or plastic cups – gardener’s favorites. Poke holes in the bottom for drainage.
• Recycle yogurt containers, milk cartons, margarine tubs, plastic jugs, egg cartons, or soda bottles. Wash thoroughly and poke holes in the bottom.
• Purchase seed-growing flats with individual cells, also known as seed cell trays. They're re-usable from year to year.
• Buy individual peat pots or peat pellets. You can transplant them into the next size pot or directly right in the ground.
• Make your own! Cut newspaper strips 12” by 6”. Wrap several strips lengthwise around a soda can (or similar-sized aluminum can) – 4” up sides, 2” across the bottom – and press tightly. Remove the can. Poof! – you’ve got a tomato pot. Or use a nifty pot maker to make strips of ordinary newspaper into biodegradable seed starting pots. Before you pack pots close together in a tray for support, make sure you poke holes in the bottom.